Neurobehavioral problems in HNRC subjects must be interpreted in the context of their medical, neurologic and immunologic status. The CAC provides other HNRC cores and projects with quantitative, longitudinal assessment of medical history, physical signs and symptoms, immunologic status, quantitative medication histories, non-medical drug exposure, cerebrospinal fluid, and staging of HIV infection. The CAC plays a leading role in conceiving, organizing, and facilitating multidisciplinary review of each visit to integrate and provide quality control of findings from each core. To help maintain continuing subject participation in the HNRC, the CAC provides to participants l)individual feedback of multidisciplinary findings and (with written consent) to their health care providers, 2) short term medical crisis management and referral, and 3) updates of treatment and research findings. The CAC assists with long term cohort maintenance by establishing frequent monitoring of subjects with advanced AIDS. This personalized attention along with bedside assessment of subjects who are critically ill assures that subjects are studied preterminally and complete autopsy studies, thus supporting the neuropathological studies of HNRC. Data from the CAC support major scientific aims of every other core and project. Furthermore, the CAC itself has scientific aims which include: 1) We will complete a series of at least two, controlled, Phase II, treatment trials of Stavudine (D4T) and other antiretroviral, antitoxic, and anticytokine drugs for patients with Minor Cognitive Motor Disorder (MCMD) to determine: a) is the cognitive component of MCMD reversible? b) do changes in virologic markers (CSF and plasma HIV-RNA) predict the response to antiretrovirals? c) is response sustained for at least 24 weeks? 2) We will extend our current clinicopathologic correlations of neuropsychologic performance to determine: a) how frequently is MCMD associated with CMV-encephalitis, HIV-encephalitis, both or neither at post mortem neuropathologic examination? b) how often does CMV-E occur in the absence of clinically recognized CMV-R or other CMV syndromes?